The best definition of architecture that has ever been given is likewise the shortest. It is "the art of building" (Viollet-le-Duc, Dict., I, 116). The art, be it observed, and not merely the act of building. And when we say the art of building, the term must be held to imply the giving to buildings of whatever beauty is consistent with their primary purpose and with the resources that may be available. As a recent writer has said: "It can hardly be held that there is one art of making things well, and another of making them badly. . . Good architecture is . . . the art of building beautifully and expressively; and bad architecture is the reverse. But architecture is the art of building in general" (Bond, Gothic architecture in England, 1). Since, however, the word building is apt to suggest, primarily, "the actual putting together of . . . materials by manual labour and machinery", it may be desirable to amend or restrict the definition given above by saying that architecture is the art of planning, designing, and drawing buildings, and of directing the execution thereof (Bond, op. cit., 2). And in this art as in all others, including that of life itself, the fundamental principle should always be that of subordinating means to ends and secondary to primary ends. Where this principle is or has been abandoned or lost sight of, the result may indeed be, or may have been, a building which pleases the eye, but it must needs be also one which offends that sense of the fitness of thing 3, which is the criterion of the highest kind of beauty. Now a church is, primarily, a building intended for the purpose of public worship; and in all sound ecclesiastical architecture this purpose should be altogether paramount. To build a church for the admiration of "the man the street", who sees it from outside, or of the tourist who pays it a passing visit, or of the artist, or of anyone else whatsoever except that of the faithful who use the church for prayer, the hearing of Mass, and the reception of the sacraments, is to commit a solecism in the liturgy of all the material arts. Even the needs of the liturgy itself are in a sense subsidiary to the needs of the faithful. Sacramenta propter homines is an old and sound saying. But, on the other hand, among the needs of the faithful must be reckoned, under normal circumstances, the adequate carrying out of the liturgy. It is, of course, perfectly true to say that a church is not only a building, in which we worship God but also itself the expression of an act of worshipful homage. This, however, it ceases to be, at least in the highest degree, unless, as has been said, the æsthetic qualities of the building have been entirely subordinated to its primary purpose. It only needs a little reflection to see that these preliminary remarks have a very practical bearing on modern church-building. There is a danger lest we should be dominated by technical terms and conventional opinions about the merits of this or that style of architecture, derived from times and circumstances that have passed away lest we should be led by sentiment or fashion, or mere lack of originality, to copy from the buildings of a bygone age without stopping to consider whether or how far the needs of our own day are those of the days when those buildings were raised. And the chief use of the study of the history of ecclesiastical architecture is not that it directs attention to a number of buildings more or less beautiful in themselves, but that it cannot fail to bring home to us that all true architectural development was inspired, primarily, by the desire to find a solution of some problem of practical utility.

Roughly speaking, all ecclesiastical architecture may be said to have been evolved from two distinct germ-cells, the oblong and the circular chamber. From the simple oblong chamber to the perfect Gothic cathedral the steps can be plainly indicated and admit of being abundantly illustrated from the actual course of architectural development in Western Europe, while the links which connect the simple circular chamber with a gigantic cruciform domed church, like St. Peter's in Rome or St. Paul's in London, are still more obvious, though the actual course of development in the case of domed churches has been far less continuous and regular.

The origins of ecclesiastical architecture

That the first place set apart for Christian worship were rooms in private dwellings is admitted on all hands; and, although it is at least doubtful whether all the texts from the New Testament which have been alleged in support of the statement will bear the interpretation that has been put upon them, the statement itself hardly needs proof. It may be assumed, further that such rooms would for the most part have a simple oblong form, with a door in one of the narrower sides. From the first, however, there must have been some kind of division between the portion of the room occupied by the officiating clergy (the thysiastesion, sanctuary, or presbytery) and the space allotted to the faithful; and this division, we may feel sure, was from a very early date marked by at least a breast-high barrier, analogous to that which still survives in the ancient cancelli of S. Clemente, Rome, and also by a curtain which veiled the altar from view during certain portions of the Liturgy. And here we find the suggestion of a first step in the development of a distinctively ecclesiastical architecture. When the first churches or chapels were erected as independent structures, an obvious economy would suggest that, especially in the case of smaller edifices, the sanctuary need not be built so broad or so high as what may already be called the nave; and an equally obvious regard for stability would suggest that the division should be marked by an arch, supporting the gable wall at the further end of the nave.

Moreover, both structural and liturgical needs would alike be served if the piers which support the dividing arch were projected inwards, somewhat beyond the side walls of the sanctuary; for the narrower the space the easier it would be to construct the arch, and to suspend a curtain from pier to pier. Thus, then, that rudimentary type of church or chapel would be reached of which archaic examples still survive in England and Ireland. Mr. Scott notes that in many of our oldest English churches there are clear indication that the opening from the nave into the sanctuary was originally much narrower than it is at present. He further notes that in the persistent adherence to the square-ended type of sanctuary which manifests itself throughout the history of English ecclesiastical architecture, may possibly be found a surviving indication of the very early introduction of Christianity into these islands.

The earliest improvement on the crude form of the oblong chamber with its rectangular annex, and one which may well have become usual even while the liturgy was confined to a single room in a private house, was to throw out a semicircular apse at the end of the chamber opposite the door, or to 8 t for the purposes of worship a room thus built. And this would almost certainly be the form adopted, at least in Rome, as soon as the Christian communities began to possess separate buildings in which to hold their religious meetings. These buildings would be, in the eyes of the public and perhaps of the law, scholae or guild-rooms; and for such buildings the form most commonly adopted appears to have been that of an oblong terminated by an apse. In the apse, of course, was placed the seat of the bishop; round the walls on either side were the subsellia of the assistant clergy, while the altar stood beneath the arch formed by the opening of the apse, or slightly in advance of it. On the hither side of the altar would be space reserved for the clerics of inferior rank, and for the schola cantorum, as soon as an organized body of singers, under whatever name, came into existence Outside the boundary of this space, however it may have been marked, the general body of the faithful would have their place, and at the lower end of this chamber, or in some kind of ante room or narthex, or possibly even in an outer court, would he placed the catechumens and  when ecclesiastical discipline was sufficiently developed  the penitents.

This particular form of the domestic church, removed by just one degree, architecturally speaking from a quite primitive simplicity, deserves special attention. For there would seem to be good grounds for the assertion that it had become at least not uncommon, even within Apostolic times. In fact, as several writers on the subject have quite independently pointed out, the main feature of the arrangement would seem to be indicated in the New Testament itself. The visions recorded in the Apocalypse are, of course, Divine revelations; but, as the vision of Ezechiel was cast in the mould of the Jewish ritual, so also those of St. John may be reasonably thought to reflect the ritual of primitive Christianity. There, then, in the midst, we see the throne, whereon there sits One enthroned, of whom the Christian bishop is the representative; and with Him are four and twenty presbyters, who are "priests" (hiereis), ranged in a semicircle (kyklothen), twelve on either hand (Revelation 4:2, 4). Within the space bounded by these seats is a pavement of glass "like to crystal" (possibly of mosaic), and in the centre the altar (Revelation 4:6; 6:9; 8:3; 9:13; 16:7). On the hither side of this are the one hundred and forty-four thousand "signed" or "sealed", who "sing a new canticle", and who incidentally bear witness to the very early origin of the schola cantorum, at least in some rudimentary form (Revelation 7:4, 14:1-3). Farther removed from the altar is that "great multitude, which no man could number, of all nations, and tribes, and peoples, and tongues", the heavenly counterpart of the coetus fidelium. (Revelation 7:9).

To lateral columns and aisles there is indeed no allusion, but it is at least possible that in the mention of the outer court which is "given unto the Gentiles" we may find the earliest traces of the atrium or parvis, which in the later ages formed part of the precincts of a fully equipped basilica (Revelation 11:2; Scott, op. cit., 31). Moreover, in these same Apocalyptic visions certain details of internal arrangement, which might perhaps have been thought to have been of comparatively late development, appear to be clearly implied. Every one is aware that in the basilicas of the fourth and succeeding centuries the altar was surmounted by a baldachin, or civory; and it is hardly less certain that the civory was not merely a canopy, but a means of support for curtains which during certain portions of the Liturgy were drawn round the altar. Traces of these ancient curtains still survive in those which flank our modern altars, in our tabernacle veils, and in the very name tabernacle, i.e. "tent", and also, curiously enough, in "those imitations of silken vallances, cast in bronze, . . . which we see in the canopies of S. Maria Maggiore and St. Peter's" (Scott, op. cit., 29). In addition to these canopy veils, however, we hear of curtains which, when drawn close, concealed the entire sanctuary from view. In the East these have, of course, been replaced by the iconostasis, a screen formerly latticed but now usually solid; while in the West they are represented, not without some change of position, by our chancel screens, and may be thought to have found another modified survival in the Lenten veil of the Middle Ages.

Now, whatever may be the case as regards the civory with its veils, there are clear indication the Apocalypse that the transverse curtains were in use from Apostolic times. For the seer thrice makes mention of a "voice" which he heard, and which preceded either "from the four horns of the golden altar" (Revelation 9:13), or "from the temple of the tabernacle of the testimony" (Revelation 15:5), or "from the throne" (Revelation 16:17). From the first of these expressions it is plain that the altar, at the moment when the voice was heard, must have been shrouded from view, and from the last it appears that the throne was likewise within the space enclosed within the veil. As regards other ritual indications in the Apocalypse, it must be sufficient barely to mention here the "souls of the martyrs" beneath the altar, the incense, the opening of the sealed book, and the garb, carefully distinguished, of the various classes of persons mentioned in the visions (Revelation 6:9; 8:3; etc.).

The basilica and basilican churches

A great deal of conjecture has been expended on the question as to the genesis of the Roman basilica. For present purposes it may be sufficient to observe that the addition of aisles to the nave was so manifest a convenience that it might not improbably have been thought of, even had models not been at hand in the civic buildings of the Empire. The most suitable example that can be chosen as typical of the Roman basilica of the age of Constantine is the church of S. Maria Maggiore. And this, not merely because, in spite of certain modern alterations, it has kept in the main its original features, but also because it departs, to a lesser extent than any other extant example, from the classical ideal. The lateral colonnade is immediately surmounted by a horizontal entablature, with architrave, frieze, and cornice all complete. The monolithic columns, with their capitals, are, moreover, homogenous, and have been cut for their position, instead of being like those of so many early Christian churches, the more or less incongruous and heterogeneous spoils of older and non-Christian edifices. Of this church, in its original form, no one  however decidedly his tastes may incline to some more highly developed system or style of architecture  will call in question the stately and majestic beauty. The general effect is that of a vast perspective of lines of noble columns, carrying the eye forward to the altar, which, with its civory or canopy, forms so conspicuous an object, standing, framed, as it mere, within the arch of the terminal apse, which forms its immediate and appropriate background.

S. Maria Maggiore is considerably smaller than were any of the other three chief basilicas of Rome (St Peter's, St. Paul's, and the Lateran). Each of these, in addition to a nave of greater length and breadth, was furnished (as may still be seen in the restored St Paul's) with a double aisle. This, however, was an advantage which was not unattended with a serious drawback from a purely esthetic point of view. For a great space of blank wall intervening between the top of the lateral colonnade and the clerestory windows was of necessity required in order to give support to the penthouse roof of the double aisle. And it is curious, to say the least, that it should not have occurred to the builders of those three basilicas to utilize a portion of the space thus enclosed, and at the same time to lighten the burden of the wall above the colonnade, by constructing a gallery above the inner aisle. It is true, of course, that such a gallery is found in the church of S. Agnese, where the low-level of the floor relatively to the surface of the ground outside may have suggested this method of construction; but whereas, in the East, the provision of a gallery (used as a gynaeceum) was usual from very early times, it never became otherwise than exceptional in the West. Taking East and West together, we find among early and medieval basilican churches examples of all the combinations that are possible in the arrangement of aisles and galleries. They are

the single aisle without gallery, which is, of course, the commonest type of all;

the double aisle without gallery, as in the three great Roman basilicas;

and finally, as a crowning example, though of a later period, the double aisle surmounted by a double gallery, as in the Duomo at Pisa.

These, however, are modifications in the general design of the building. Others, not less important, though they are less obviously striking, concern the details of the construction. Of these the first was the substitution of the arch for the horizontal entablature, and the second that of the pillar of masonry for the monolithic column. The former change, which had already come into operation in the first basilica of St. Paul without the Walls, was so obviously in the nature of an improvement in point of stability that it is no matter for surprise that it should have been almost universally adopted. Colonnaded and arcaded basilicas, as we may call them, for the most part older than the eleventh century, are to be found in the most widely distant regions, from Syria to Spain, and from Sicily to Saxony; and the lack of examples in Southern France is probably due to the destructive invasion of the Saracens and Northmen and to the building of new churches of a different type, in the eleventh and succeeding centuries, on the ruins of the old. The change from column to pillar, though in many cases it was no doubt necessitated by lack of suitable materials  for the supply of ready-made monoliths from pagan buildings was not inexhaustible  proved, in fact, the germ of future development; for from the plain square support to the recessed pillar, and from this again to the grouped shafts of the Gothic cathedrals of later times, the progress can be quite plainly traced.

Mention should here be made of a class of basilican churches, in which as in S. Miniato, outside Florence, and in S. Zenone, Verona, pillars or grouped shafts alternate, at fixed intervals, with simple columns, and serve the purpose of affording support to transverse arches spanning the whole width of the nave; a first step, it may be observed, to continuous vaulting.

Romanesque types

Something must now be said of the very important alterations which the eastern end of the basilican church underwent in the process of development from the Roman to what may conveniently be grouped together under the designation of "Romanesque" types. When, in studying the ground-plan of a Roman basilica, we pass from the nave and aisles to what lies beyond them, only two forms of design present themselves. In the great majority of instances the terminal apse opens immediately on the nave, with the necessary result, so far as internal arrangements are concerned, that the choir, as we should call it, was an enclosure, quite unconnected with the architecture of the building, protruding forwards into the body of the church, as may still be seen in the church of S. Clemente in Rome. In the four greater basilicas, however, as well as in a few other instances, a transept was interposed between the nave and the apse, affording adequate space for the choir in its central portion, while its arms (which did not project beyond the aisles) served the purpose implied in the terms senatorium and matroneum. Now it is noteworthy that the transept of a Roman basilica is, architecturally speaking, simply an oblong hall, crossing the nave at its upper extremity, and forming with it a T-shaped cross, or crux immissa, but having no organic structural relation with it. But it was only necessary to equalize the breadth of transept and nave, so that their crossing became a perfect square, in order to give to this crossing a definite structural character, by strengthening the pieces at the four angles of the crossing, and making them the basis of a more or less conspicuous tower. And this was one of the most characteristic innovation or improvements introduced by the Romanesque builders of Northern Europe. In fact, however, before this stage of development was reached, the older basilican design had undergone another modification. For the simple apse, opening immediately to the transept, church builders of all parts of Europe had already in the eighth century substituted a projecting chancel, forming a fourth limb of the cross, which now definitively assumed the form of the crux commissa, by contrast with the crux immissa of the Roman basilica. The earliest example of a perfectly quadrate crossing, with a somewhat rudimentary tower, appears to have been the minster of Fulda, built about A.D. 800. It was quickly followed by St. Gall (830), Hersfeld (831), and Werden (875); but nearly two centuries were to elapse before the cruciform arrangement, even in the case of more important churches, can be said to have gained general acceptance (Dehio and v. Bezold, Die kirchliche Baukunst des Abendlandes, I, 161).

The differences which have already been mentioned were, however, by no means the only ones which distinguished the Romanesque from the Roman transept. The transept of a Romanesque church, especially of those which were attached to monasteries, was usually provided with one or more apses, projecting from the east side of its northern and southern arms; and from this it appears, plainly enough, that the purpose, or at least a principal purpose, of the medievaltransept, was to make provision for subsidiary altars and chapels. A pair of transeptapses, projecting eastwards, already makes its appearance at Hersfeld and Werden. At Bernay, Boscherville (St-Georges), and Cerisy-la-Forêt (St-Vigor), each arm of the transept has two eastern apses, corresponding respectively to the aisle and to the projecting arm. The same arrangement is found also at Tarragona. At La Charité, a priory dependent on Cluny, each arm had three apses, so that there were seven in all, immediately contiguous to one another, and varying in depth from the central to the northern and southern members of the system. The plan of Cluny itself was that of a cross with two transverse beams. Of the western transept each arm had two apses; of the eastern each had three, two projecting eastwards and one terminal. Saint-Benoît-sur-Loire had likewise a double transept, furnished on the same principle with six subsidiary apses. Among Englishcathedrals  it may here be mentioned  both Canterbury and Norwich have a single chapel projecting from each arm of their respective transepts; and at Ely the "Galilee" porch, which has the form of a western transept, opens eastwards into two apsidal chapels, contiguous on either side to the main walls of the cathedral.

Far more important in their bearing on the later history of architecture than these developments of the transept were certain changes which gradually took place in connection with the chancel. It is not unusual in Romanesque churches, to find the chancel flanked, like the nave, with aisles, terminating in apsidal or square-ended chapels. But in more considerable edifices especially in France, the aisle is often carried round as an ambulatory behind the chancelapse; and when this is the case, the ambulatory most commonly opens into a series of radiating chapels. These are, in the earliest examples, entirely separate from one another, being sometimes two or four, but more usually three or five, in number. In later examples the number of chapels increases to seven or even nine; and they are then contiguous, forming a complete corona or chevet.

The first beginnings of this system go back to so early a date as the fifth century. De Rossi has argued, apparently on good grounds, that some early Roman, Italian, and African basilicas were furnished with an ambulatory round the apse. This form of design, however, was soon abandoned in Italy, and in the Romanesque pre-Gothic period it cannot be said to have been usual anywhere except in France, where it proved a seed rich with the promise of future developments. The earliest instance of its adoption there was almost certainly the ancient church of St-Martin of Tours, as rebuilt by Bishop Perpetuus in A.D. 470. This edifice, as Quicherat has shown, had a semicircular ambulatory at the back of the altar, in which, a few years later, was placed the tomb of Perpetuus himself. From Tours the type seems to have passed to Clermont-Ferrand (Sts. Vitalis and Agricola), and thence, many centuries later, to Orléans (St-Aignan, 1029). Meanwhile, in 997, the church of St. Martin had been rebuilt, and in the foundations of this edifice, which can still be traced, we find what is probably the earliest example of a chevet or corona of radiating chapels. It served, in its turn, in the course of the following century, as the model, in this respect, of Notre-Dame de la Couture at Le Mans (c. 1000), St-Remi at Reims (c. 1010), St-Savin at Saint Savin (1020-30), the cathedral at Vannes (c. 1030), St-Hilaire at Poitiers (1049), and the abbey church at Cluny, as rebuilt in 1089. Shortly before 1100 the church of St. Martin was once more rebuilt, on a scale of greater splendour; and once more the new building became the model for other churches, chief among which were those of St-Sernin at Toulouse (1096), of Santiago at Compostela (c. 1105), and of the cathedral at Chartres (1112).

Romanesque vaulting

The history of ecclesiastical architecture in Western Europe during the relatively short period which alone deserves to be regarded as one of more or less continuous and steady advance, and which extends, roughly speaking, from 1000 to 1300, may be described as the history of successive and progressive attempts to solve the problem, how best to cover with stone vaulting a basilican or quasi-basilican church, that is to say, a building of which the leading feature is a nave flanked with aisles and lighted with clerestory windows (Dehio and v. Bezold, op. cit. I, 296; Bond, op. cit., 6). It was the conditions of this problem, and the failure, more or less complete, of all previous attempts to solve it satisfactorily, and by no means a mere æsthetic striving after beauty of architectural form, which led step by step to the development of the Gothic architecture of the thirteenth century in its unsurpassed and unsurpassable perfection.

The advantages of a vaulted, as compared with a timber, roof are so obvious that we are not surprised to find, dating from the tenth century or at latest from the beginning of the eleventh, examples of basilican churches with vaulted aisles. Indeed these first attempts at continuous vaulting would probably have been made much earlier, but for the invasions of Saracens and Northmen, which delayed till that period the first beginnings of a steady development in ecclesiastical architecture, but which by their wholesale destruction of pre-existing buildings may be said to have prepared the way for that same development. The vaulting of the nave, however, in the case of any church of considerable size, was a very different matter; and it was not until the eleventh century was well advanced that the problem was seriously faced. And when at last it was definitely taken in hand, this was done under pressure of dire necessity. Everyone who is at all conversant with medieval chronicles, or with the history of the cathedrals of Western Europe, must be aware how extremely frequent were the disasters caused by conflagrations, and it was natural enough that the church-builders of the later Middle Ages should aim at making their buildings, at least relatively, fire-proof.

The simplest form which the vaulting of a rectangular chamber can take is, of course, the cylindrical barrel-vault; and this is, in fact, the form which was adopted in many of the earliest examples of vaulted roofs, especially in the south of France; a form, too, which was extensively used in Italy during the age of the Renaissance. But, though simplest alike in conception and in construction, the cylindrical barrel-vault is in fact the least satisfactory that could be devised for its purpose; and the objections which militate against its employment are equally valid against that of the barrel-vault whose cross section forms a pointed arch. Of these objections the chief is that the horizontal thrust of a barrel-vault is evenly distributed throughout its entire length. Theoretically, then, this thrust requires to be met, not by a series of buttresses, but by a continuous wall of sufficient thickness to resist the outward pressure at any and every point along the line. Moreover, the higher the wall, the greater is the thickness needed, assuming of course that the wall stands free, like the clerestory wall of an aisled church. Much, too, will depend on the cohesiveness of the vaulting itself; and as the Romanesque church-builders were either unacquainted with, or unable to use, the methods by which the Romans and the Byzantines respectively contrived to give an almost rigid solidity to their masonry, it is no matter for surprise that in two large classes of instances they should have been content to sacrifice either the clerestory or the aisles to the advantages of a vaulted roof and to the exigencies of stability. Of aisleless churches indeed, we must forbear here to speak. But of an important group of buildings which German writers have designated Hallenkirchen (hall-churches) a word must be said, as they unquestionably played a part in preparing the way for the final solution of the problem of vaulting.

The most rudimentary form of hall-church is that in which the nave and aisles are roofed with three parallel barrel-vaults, those of the aisles springing from the same level as those of the nave. Examples are found at Lyons (St-Martin d'Ainay), at Lesterps, at Civray, and Carcassonne (St-Nazaire). An improvement on this design, in view of the illumination of the nave, consists in giving to the vaulting of the aisles the form of a "rampant" arch, as at Silvacanne, and from this it was but a step to the arrangement by which the section took the form of a simple quadrant as at Parthenay-le-Vieux, Preuilly, and Fontfroide. This method of quadrant vaulting, as Viollet-le-Duc and others have observed, provides a kind of continuous internal "flying buttress", though it is by no means certain that the idea of the flying buttress in the Gothic architecture of Northern France was actually suggested by these Southern buildings. In point of stability, the hall-churches of the eleventh century leave nothing to be desired. Their great defect is want of light. And this defect almost equally affects a class of buildings which may be described as two-storied hall-churches, and which are found principally, if not exclusively, in Auvergne and its neighbourhood. These are furnished, like a few of the Roman basilicas and certain Byzantine churches, with a gallery, which is not a mere triforium contrived in the thickness of the walls, but a chamber of equal dimension with the aisle. This arrangement not only affords additional spaces but also, by reason of the greater height of the edifice, might seem to facilitate the provision of a more liberal supply of light, unimpeded by neighbouring buildings. This last mentioned advantage is, however, almost entirely negatived by the circumstance that, in this class of buildings, each bay of the gallery is subdivided by means of coupled or grouped arches, so that the additional obstruction offered to the passage of the light almost entirely counterbalance the possible gain through additional fenestration. We say "the possible gain" because, in fact, the galleries of these churches are but sparingly provided with windows. In these churches (which to the English reader should be of special interest by reason of their affinity in point of construction to the Westminster cathedral) the aisle is usually cross-vaulted, while the gallery has a quadrant vault abutting in the wall of the nave just below the springing of the transverse arches. The most noteworthy examples are found at Clermont-Ferrand (Notre Dame du Port), Issoire (St-Paul), and Conques. To the same family belongs moreover, the great church of St-Sernin at Toulouse already mentioned, which is distinguished from those previously named by having a double aisle. At Nevers the church of St-Etienne resembles those at Clermont, Issoire, and Conques, except that it is provided with a range of upper windows which break through the barrel-vaulting, somewhat after the fashion which afterwards became so common in Italy in churches of the Renaissance period.

The inherent shortcomings of the barrel-vault, especially when used as a roof for the nave of an aisled church, have been sufficiently illustrated. These disadvantages, so far as structural stability and fenestration are concerned, might indeed be overcome by adopting the system of a succession of transverse barrel-vaults, such as are seen in the unique instance of the church of St-Philibert at Tournus. Such a construction is, however, "ponderous and inelegant, and never came into general use" (Moore, Gothic Architecture, 42). The system of cross-vaulting, which has now to be considered, may be regarded as a combination of longitudinal with transverse barrel-vaulting, inasmuch as it may be described as consisting of a central barrel which is penetrated or intersected by a series of transverse vaults, corresponding of course to the successive bays or compartments of the nave. The advantages of cross-vaulting are threefold. In the first place the total amount of the outward lateral thrust is very greatly diminished, since one half of it is now replaced by longitudinal thrusts, which, being opposed in pairs, neutralize one another. Secondly, all that is left of the lateral thrust, as well as the longitudinal thrusts, and the whole of the vertical pressure instead of being distributed throughout the whole length of the building, is now collected and delivered at definite points, namely the summits of the columns or pillars. Thirdly and lastly, a perfectly developed system of cross-vaulting makes it possible so to heighten the clerestory windows that their archivolts shall reach the utmost interior height of the building, and so to broaden them that their width between reveals may approximate very closely to the interval between column and column below. By these improvements (as ultimately realized in the perfected Gothic of the thirteenth century) the somewhat rudimentary design of the ancient Roman basilica may be said to have reached the highest development of which it is capable. The gradual development of cross-vaulting it is to be observed, did not take place in those districts of Southern and Central France which had already become the home of the barrel-vault and to a less degree of the cupola, but first in Lombardy then in Germany, and finally in Northern France and in England. In these countries the evolution of the Romanesque timber-roofed basilican church had  with local variations of course  reached a far more advanced stage than was ever attained in these regions in which the adoption of barrel-vaulting at a relatively early date had in a manner put a check on architectural progress. And it is noteworthy that in Lombardy and Germany, when cross-vaulting was first adopted, its development was far less complete than in Northern France, and that in like manner the advance towards perfection was both less rapid and less complete in Normandy than in Picardy and the Ile-de-France. These two districts were the last to adopt the system, but it was here that it was within the brief space of less than fifty years (1170-1220), brought to its final perfection. The reason may probably have been, as Dehio and von Bezold suggest, that the architects of the Ile-de-France, in the days of Philip Augustus and St. Louis, were less trammelled than those of Normandy by the traditions of a school. The comparative lack of important architectural monuments of an earlier date left them, say these writers, a more open field for their inventive enterprise (op. cit. I, 418).

The simplest form of cross-vaulting is of course that which is formed by the intersection of two cylindrical barrel-vaults of equal span. And this, without the use of ribbed groining, was the method mostly adopted by the Roman builders in their civic edifices. In the case of a pillared or columned church, however, this method had its disadvantages. In particular, having regard to the dimensions of the aisle and its vaulting, the builders of Northern Europe had all but universally adopted the plan of so spacing the columns and pillars which flank the nave that the intervals between them should be one-half the width of the church. Now the only means by which an equal height could be given to vaults of unequal span was the use of the pointed arch; and so it came about that the pointed arch was adopted, not primarily for æsthetic reasons, but rather for constructive purposes. And the same is to be said of the use of ribbed groining. The medieval builders, who, as has been said above, possessed neither a tenacious mortar nor the command of an abundant supply of rough labour, and who therefore could not  even had they wished it  have adopted the massive concrete masonry of the Romans, were driven by the very necessities of the case to aim at the same time to depend for stability not on the cohesion of the materials, but on the reduction of thrusts to a minimum, and on their skilful transmission to points where they could be effectively resisted. It was, then, plainly desirable to substitute for a vaulting of uniform thickness a framework of ribs on which a comparatively thin layer of stones (cut to the requisite curvature) could be laid, and as far as possible to lighten the whole construction by moulding the ribs and likewise the columns which supported the vaulting. The same principle of aiming at lightness of construction led to the elimination, as far as possible, of arches of the nave. This was done by the enlargement of the windows and the development of the triforium, till the entire building, with the exception of the buttresses, and of the spandrels below the triforium, became a graceful framework of grouped shafts and interlacing ribs (Moore, op. cit., 17). The final stage in the evolution of architecture of the pointed arch was not, however, reached, until, for the solid Romanesque buttresses, which rested on the vaulting of the aisles, and which were not only clumsy but often proved inadequate for their purpose, the genius of the Gothic builders hit upon the epoch-making device of the flying buttress. By means of this device the thrust of the main vaulting was not, indeed, as has been too often said, "met by a counter-thrust", but was transmitted to the solid buttresses, mostly weighted with pinnacles, which were now built outwards to a great distance from the aisles, and the spaces between which were sometimes utilized, and might with advantage have been more often utilized, for a range of lateral chapels. The subject of Gothic architecture in its details is, however, one that needs separate treatment, and for present purposes this very inadequate indication of some of the general principles involved in its development must suffice.

The circular church and its derivatives

It was stated at the outset of the article that all ecclesiastical architecture may be said to have been developed from two primitive germs, the oblong and the circular chamber. Of those very numerous churches, principally, but by no means exclusively, Eastern or Italian, which may be regarded as the products of the second line of development, we shall speak very briefly. That a circular chamber without any kind of annex was unsuitable for the ordinary purposes of public worship is plain enough. And the most obvious modification of this rudimentary form was to throw out a projecting sanctuary on one side of the building, as in St. George's, Thessalonica, or in the little church of S. Tommaso in Limine, near Bergamo. It was hardly less obviously convenient to build a projecting porch or narthex on the opposite side, as in St. Elias's, also at Thessalonica, and to complete the cross by means of lateral projection, as in the sepulchral chapel of Galla Placidia at Ravenna. Thus it was that churches having the form of a Greek cross, as well as other varieties of what German authors call the Centralbau, may be said to owe their origin to a very simple process of evolution from the circular domed building. Among the almost endless varieties on the main theme may be here enumerated:

buildings in which a circular, or polygonal, or quadrilateral aisle, whether in one or more stories, surrounds the central space,

buildings in which, though the principal open space is cruciform, and the whole is dominated by a central cupola, the ground-plan shows a rectangular outline, the cross being, as it were, boxed within a square; and

buildings in which one of the arms of the cross is considerably elongated, as in the Duomo at Florence, St. Peter's in Rome, and St. Paul's in London.

The last-named modification, it is to be observed, has the effect of assimilating the ground-plan of those great churches, and of many lesser examples of the same character, to that of the Romanesque and Gothic cruciform buildings whose genealogical descent from the columned rectangular basilica is contestable. Among ecclesiastical edifices of historical importance or interest which are either circular or polygonal, or in which the circular or polygonal centre predominates over subsidiary parts of the structure, may be mentioned the Pantheon in Rome, St. Sergius at Constantinople, S. Vitale at Ravenna, S. Lorenzo at Milan, the great baptisteries of Florence, Siena, and Pisa, and the churches of the Knights Templars in various parts of Europe. St. Luke at Stiris in Phocis, besides being an excellent typical instance of trueByzantine architecture, affords a good example of the "boxing" of a cruciform building of the Greek type, by enclosing within the walls the square space between the adjacent limbs of the cross.

Practically, however, the full development of cruciform from circular buildings became possible only when the problem had been solved of roofing a square chamber with a circular dome. This has in some cases been done by first reducing the square to an octagon, by means of "squinches" or "trompettes", and then raising the dome on the octagon, by filling in the obtuse angles of the figure with rudimentary pendentives or faced corbelling. But already in the sixth century the architect and builder of Santa Sophia had showed for all time that it was possible by means of "true" pendentives, to support a dome, even of immense size, on four arches (with their piers) forming a square. The use of pendentives being once understood, it became possible, not only to combine the advantages of a great central dome with those of a cruciform church, but also to substitute domical for barrel-vaulting over the limbs of the cross, as at S. Marco, Venice, St-Front, Périgueux, and S. Antonio, Padua, or even to employ domical vaulting for a nave divided into square bays, as in the cathedral at Angoulême and other eleventh century churches in Perigord, in S. Salvatore at Venice, in the London Oratory, and (with the difference that saucer domes are here employed) in the Westminster Cathedral. Nor should it be forgotten that in the nave of St. Paul's, London, the architect had shown that domical vaulting is possible even when the bays of nave or aisles are not square, but pronouncedly oblong. Indeed, if account be taken of the manifold disadvantages of barrel-vaulting as a means of roofing the nave of a large church, it may safely be said that the employment of some form of the dome or cupola is as necessary to the logical and structural perfection of the architecture of the round arch as ribbed groining and the use of flying buttresses are necessary to the logical and structural perfection of the architecture of the pointed arch.

Systems and styles of architecture in religion to modern needs

A word must now be said, in conclusion, as to the merits of the several systems and styles of architecture, more especially in relation to the needs of our own day. Of systems, indeed, there are in truth only three, the trabeate or that of which the horizontal lintel may be regarded as the generating element, and which of necessity postulates a timber roof; that of the round arch, which by virtue of the law of economy postulates, as has been said, the use of domical rather than barrel-vaulting and that of the pointed arch, which, if carried to perfection postulates ribbed groining and the use of the flying buttress. The second system, however, admits of two methods of treatment which are sufficiently distinctive to be classed as two "styles", viz. the neoclassical, or Renaissance, and the Byzantine, and which shall be particularized presently.

Now the trabeate system, or that of the timber roof, may be very briefly dismissed. In the great majority of cases we must, indeed, of necessity be content with such a covering, for our churches; but no one would choose a wooden roof who could afford a vaulted building. Again, the various types of Romanesque architecture, with their imperfect and tentative methods of vaulting, though historically of great interest, should be regarded as finally out of court. On the other hands of the Gothic architecture of the thirteenth century as exemplified in the great cathedrals of Northern France and of Cologne, it mas be quite fearlessly asserted:

that every single principle of construction employed therein was the outcome of centuries of practical experience, in the form of successive and progressive attempts to solve the problems of church vaulting;

that the great loftiness of these buildings was not primarily due (as has been sometimes suggested) to any mere Emporstreben, or "upward-soaring" propensity, but was simply the aggregate result of giving to the windows of the aisles and of the clerestory a height in suitable proportion to their width, and to the triforium a height sufficient to allow of the abutment of the aisle roof; and

that every subsequent attempt to modify in any substantial particular, this perfected Gothic style, was of its nature retrogressive and decadent, as may be illustrated from the English perpendicular and the Italian and Spanish varieties of Gothic architecture.

Nevertheless it must be admitted that thirteenth-century Gothic, though perfect of its kind, has its limitations, the most serious of which  in relation to modern needs  is the necessarily restricted width of the nave. When the architect of the Milancathedral attempted to improve on his French predecessors by exceeding their maximum width of fifty feet, and to construct a Gothic building with a nave measuring sixty feet across it was found impossible, as the building proceeded, to carry out the original design without incurring the almost certain risk of a collapse, and hence it was necessary to depress the clerestory to its present stunted proportions. Now under modern conditions of life, especially in the case of a cathedral of first-class importance, a nave of far greater width is by all means desirable; and in order to secure this greater width it is necessary either to fall back on the unsatisfactory compromise of Italian or Spanish Gothic, as illustrated in the cathedrals of Milan, Florence, or Gerona, or else to adopt the principle of the round arch, combined, by preference, with domical vaulting. This, as everyone knows, is what Mr. Bentley has done, with altogether conspicuous success, in the case of the Westminster Cathedral. Of the design of this noble edifice it is impossible to speak here. But it may be worth while to indicate one main reason for the choice of the Byzantine rather than the neoclassic or Renaissance treatment of the round-arch system. The principal difference between the two is this: that, whereas the neoclassical style, by its use of pilasters, treats every pier as though it were a cluster of huge, flat-faced columns; the Byzantine boldly distinguishes between piers and columns, and employs the latter exclusively for the purposes which monolithic shafts are suited to fulfil, for instance the support of a gallery while the piers in a Byzantine building make no pretence of being other than what they are, viz., the main supports of the vaulting. The Byzantine method of construction was employed at Westminster has the further advantage that it brings within the building the whole of the spaces between the buttresses thereby at the same time increasing the interior dimensions and avoiding the awkward appearance of ponderous external supports. Nor is the Byzantine style of architecture suitable for a great cathedral alone; and one may venture to hope that the great experiment which has been tried at Westminster will be fruitful of results in the future development of ecclesiastical architecture.

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